Poor electrocatalytic activity and carbon monoxide (CO) poisoning of the anode in Pt-based catalysts are still two major challenges facing direct methanol fuel cells. Herein, we demonstrate a highly active and stable Pt nanoparticle/Mo2C nanotube catalyst for methanol electro-oxidation. Pt nanoparticles were deposited on Mo2C nanotubes using a controllable atomic layer deposition (ALD) technique. This catalyst showed much higher catalytic activity for methanol oxidation and superior CO tolerance, when compared with those of the conventional Pt/C and PtRu/C catalysts. The experimental evidence from X-ray absorption near-edge structure spectroscopy and scanning transmission X-ray microscopy clearly support a strong chemical interaction between the Pt nanoparticles and Mo2C nanotubes. Our studies show that the existence of Mo2C not only minimizes the required Pt usage but also significantly enhances CO tolerance and thus improves their durability. These results provide a promising strategy for the design of highly active next-generation catalysts.

Na3[Ti2P2O10F] was synthesized by a hydrothermal method. It has an open framework structure consisting of TiFO5 octahedra and PO4 tetrahedra. The feasibility of Na3[Ti2P2O10F] as an anode material for lithium-ion batteries was first studied. Na3[Ti2P2O10F] exhibits a reversible capacity of more than 200 mAh g–1 at a discharge/charge current rate of 20 mA g–1 (∼0.1 C) and 105 mA g–1 at a discharge/charge current rate of 400 mA g–1 (∼2 C) with a lower intercalation voltage. The result of in situ X-ray diffraction test shows the structural evolution during the first discharge/charge cycle. The structure of Na3[Ti2P2O10F] was kept during discharge/charge with a slight change of the lattice parameters, which indicates a lithium solid solution behavior.Keywords: anode material; lithium-ion battery; Na3[Ti2P2O10F]; structural evolution

A new perovskite cathode, Sr0.95Ce0.05CoO3−δ, performs well for oxygen-reduction reactions in solid oxide fuel cells (SOFCs). We gain insight into the crystal structure of Sr1–xCexCoO3−δ (x = 0.05, 0.1) and temperature-dependent structural evolution of Sr0.95Ce0.05CoO3−δ by X-ray diffraction, neutron powder diffraction, and scanning transmission electron microscopy experiments. Sr0.9Ce0.1CoO3−δ shows a perfectly cubic structure (a = a0), with a large oxygen deficiency in a single oxygen site; however, Sr0.95Ce0.05CoO3−δ exhibits a tetragonal perovskite superstructure with a double c axis, defined in the P4/mmm space group, that contains two crystallographically different cobalt positions, with distinct oxygen environments. The structural evolution of Sr0.95Ce0.05CoO3−δ at high temperatures was further studied by in situ temperature-dependent NPD experiments. At 1100 K, the oxygen atoms in Sr0.95Ce0.05CoO3−δ show large and highly anisotropic displacement factors, suggesting a significant ionic mobility. The test cell with a La0.8Sr0.2Ga0.83Mg0.17O3−δ-electrolyte-supported (∼300 μm thickness) configuration yields peak power densities of 0.25 and 0.48 W cm–2 at temperatures of 1023 and 1073 K, respectively, with pure H2 as the fuel and ambient air as the oxidant. The electrochemical impedance spectra evolution with time of the symmetric cathode fuel cell measured at 1073 K shows that the Sr0.95Ce0.05CoO3−δ cathode possesses superior ORR catalytic activity and long-term stability. Mixed ionic–electronic conduction properties of Sr0.95Ce0.05CoO3−δ account for its good performance as an oxygen-reduction catalyst.

In this work, sub-stoichiometric tungsten oxide W18O49 was first studied as a support for a Pt catalyst. Metallic monoclinic W18O49 nanorods (NRs) with an isotropic morphology can not only improve electron, reactant, and product transport but can also enhance the utilisation of Pt for the methanol oxidation reaction (MOR). The specific activity for the forward peak (If) of Pt/W18O49 was determined to be 1.14 mA cmPt−2, which is approximately 1.4 and 1.8 times higher than that of Pt-black and Pt/C, respectively. On the other hand, the robust W18O49 NRs improve the stability of Pt/W18O49. After a 5000-cycle accelerated durability test, the electrochemical surface area (ECSA) loss rate of Pt/W18O49 was only 27.12%, less than that of Pt-black and Pt/C. Moreover, numerous oxygen vacancies and two valence states of W (W5+ and W6+) were found to co-exist in W18O49, which may promote hydrogen spillover and oxygen buffering. These effects together contributed to improve the anti-poisoning properties of Pt/W18O49 towards the intermediates in the MOR. The peak current ratio of the forward versus the backward (If/Ib) reaction is 1.12 for Pt/W18O49, 0.99 for Pt-black, and 0.79 for Pt/C. It was found that the Magnéli phase W18O49 may be a promising catalyst support for use in the MOR.

A facile hydrothermal route has been developed to prepare graphene–Co3O4 nanocomposites. The graphene–Co3O4 nanocomposite catalyst demonstrates an excellent catalytic activity toward oxygen-reduction reaction including a considerably more positive half-wave potential (−0.23 V) than that of pristine graphene (−0.39 V), as well as higher cathodic currents. More importantly, this catalyst shows better long-term durability than the commercial Pt/C catalyst in an alkaline solution. The preliminary results indicate that the graphene–Co3O4 nanocomposite is an efficient and stable bifunctional catalyst for Li–air batteries and may be an alternative to the high-cost commercial Pt/C catalyst for the ORR/OER in alkaline solutions.

•Prepare a novel MoO3 nanorods/Fe2(MoO4)3 nanoparticles composite material.•Study on its electrochemical behavior as an alternative anode for SOFC applications.•Demonstrate the potential of this composite as an anode for SOFCs with hydrocarbon fuels.MoO3 nanorods/Fe2(MoO4)3 nanoparticles composite has been prepared by a hydrothermal method combined with an in situ diffusion growth process. Single cells based on 300 μm LSGM electrolyte have been fabricated with the MoO3 nanorods/Fe2(MoO4)3 nanoparticles composite anode and a composite cathode consisting of Sr0.9Ce0.1CoO3−δ and Sm-doped ceria (SDC). The peak power densities reach 225, 50, 75 mW cm−2 at 900 °C in H2, CH4 and C3H8, respectively. The cell shows excellent long-term stability at 850 °C. The preliminary results demonstrate that the MoO3 nanorods/Fe2(MoO4)3 nanoparticles composite is a promising alternative anode for solid oxide fuel cells.MoO3 nanorods/Fe2(MoO4)3 nanoparticles composite anode for SOFCs with hydrocarbon fuels.

Perovskite Sr1–xCexCoO3−δ (0.05 ≤ x ≤ 0.15) have been prepared by a sol–gel method and studied as cathodes for intermediate temperature solid oxide fuel cells. As SOFC cathodes, Sr1–xCexCoO3−δ materials have sufficiently high electronic conductivities and excellent chemical compatibility with SDC electrolyte. The peak power density of cells with Sr0.95Ce0.05CoO3−δ is 0.625 W cm–2 at 700 °C. By forming a composite cathode with an oxygen ion conductor SDC, the peak power density of the cell with Sr0.95Ce0.05CoO3−δ-30 wt %SDC composite cathode, reaches 1.01 W cm–2 at 700 °C, better than that of Sm0.5Sr0.5CoO3-based cathode. All these results demonstrates that Sr1–xCexCoO3−δ (0.05 ≤ x ≤ 0.15)-based materials are promising cathodes for an IT-SOFC.Keywords: composite cathode; intermediate temperature; oxygen-reduction reaction; solid oxide fuel cell; Sr1−xCexCoO3−δ;

Porous flowerlike Co3O4 microspheres/Cu nanoparticles composite has been synthesized via a combined solvothermal method, subsequent thermal treatment and polyol process. Due to the 3D mesoporous structure, the resulting Co3O4 microspheres/Cu catalyst shows an efficient and stable bifunctional catalytic activity. The cobalt oxide-based catalysts show better performance during the discharging and charging processes at a current density of 0.05 mA cm− 2 compared with that of the Vulcan XC-72. The cell with this novel catalyst can be reversibly charged/discharged and has a good cycle performance. The preliminary results indicate that the Porous flowerlike Co3O4 microspheres/Cu nanoparticles composite is a promising material for a metal/air battery or a PEM fuel cell as an efficient and stable bifunctional catalyst.Highlights► Prepare a porous micro/nanostructured composite material consisting of flowerlike Co3O4 microsphere and Cu nanoparticles. ► Study on the catalytic behavior of this novel catalyst in a hybrid electrolyte system. ► Demonstrate its potential application in a lithium-air battery as an efficient and stable bifunctional catalyst.

•The hollow LSCF cathode materials have been successfully synthesized.•GDC-impregnated LSCF tubes display larger TPB region and higher porosity.•The lowest ASR value of LSCF/GDC cathode is 0.07 Ω cm2 at 650 °C.In order to reduce the polarization resistance of the cathode, we have developed one-dimensional (1D) nanostructured La0.8Sr0.2Co0.2Fe0.8O3−δ (LSCF) tubes/Ce0.8Gd0.2O1.9 (GDC) nanoparticles composite cathodes for solid oxide fuel cell. Uniform LSCF/PVP composite nanofibers have been firstly synthesized by a single-nozzle electrospinning technique, followed by firing at 800 °C for 2 h to form one-dimensional LSCF tubes. Subsequently, the GDC phases were introduced into tube structured LSCF scaffold pre-sintered on a GDC pellet by a multi-impregnation process. Electrochemical Impedance spectra reveal that nanostructured LSCF tubes/GDC nanoparticles composite cathodes have a better electrochemical performance, achieving area-specific resistances of 4.70, 1.12, 0.27 and 0.07 Ω cm2 at 500, 550, 600 and 650 °C for the composite of GDC and LSCF in a weight ratio of 0.52:1. The low ASR values are mainly related to its optimal microstructure with larger triple-phase boundaries and higher porosity. These results suggest that LSCF tube/GDC nanoparticle composite can be an alternative cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).

The controllable synthesis of nanostructured CeO2-based materials is an imperative issue for environment- and energy-related applications. In this review, we present the recent technological and theoretical advances related to the CeO2-based nanomaterials, with a focus on the synthesis from one dimensional to mesoporous ceria as well as the properties from defect chemistry to nano-size effects. Seven extensively studied aspects regarding the applications of nanostructured ceria-based materials are selectively surveyed as well. New experimental approaches have been demonstrated with an atomic scale resolution characterization. Density functional theory (DFT) calculations can provide insight into the rational design of highly reactive catalysts and understanding of the interactions between the noble metal and ceria support. Achieving desired morphologies with designed crystal facets and oxygen vacancy clusters in ceria via controlled synthesis process is quite important for highly active catalysts. Finally, remarks on the challenges and perspectives on this exciting field are proposed.

In the paper, we find that graphene has a strong dielectric loss, but exhibits very weak attenuation properties to electromagnetic waves due to its high conductivity. As polyaniline nanorods are perpendicularly grown on the surface of graphene by an in situ polymerization process, the electromagnetic absorption properties of the nanocomposite are significantly enhanced. The maximum reflection loss reaches −45.1 dB with a thickness of the absorber of only 2.5 mm. Theoretical simulation in terms of the Cole–Cole dispersion law shows that the Debye relaxation processes in graphene/polyaniline nanorod arrays are improved compared to polyaniline nanorods. The enhanced electromagnetic absorption properties are attributed to the unique structural characteristics and the charge transfer between graphene and polyaniline nanorods. Our results demonstrate that the deposition of other dielectric nanostructures on the surface of graphene sheets is an efficient way to fabricate lightweight materials for strong electromagnetic wave absorbents.

Sr0.95Ce0.05CoO3−δ (SCCO) particles loaded with copper nanoparticles on their surface are shown to be excellent, low-cost, and stable bifunctional catalysts for the oxygen-reduction and oxygen-evolution reactions (ORR and OER) in aqueous solution. Evidence for the presence of Ce3+ and Co2+ as well as Co4+ and Co3+ ions revealed by XPS measurements as well as XRD analysis indicates that a CeCoO2.5 brownmillerite phase may be extruded to the surface. A surface Co4+/Co3+ couple is known to be a good OER catalyst. The performance of the SCCO-based catalysts is better at higher current rates (>0.1 mA cm−2) than that of Vulcan XC-72 and even close to that of the 50% Pt/carbon-black catalyst. This catalyst could be used in a metal/air battery or a PEM fuel cell as an efficient and stable bifunctional catalyst.

In situ diffusion growth of Fe2(MoO4)3 nanocrystals on the surface of α-MoO3 nanorods was achieved through a facile method. The obtained Fe2(MoO4)3@α-MoO3 nanorods exhibit significantly enhanced ethanol sensing properties compared with those of the pristine α-MoO3 nanorods and the Fe2(MoO4)3 nanoparticles, which are attributed to the improved catalytic properties of Fe2(MoO4)3 at low temperature.

Graphene/porous cobalt nanocomposite was successfully prepared through a facile method, whose hydrogen storage capacity was up to 241.9 mA h g−1 at room temperature, higher than those of graphene and commercial cobalt.

A solvothermal method was developed to prepare on a large scale monodisperse porous β-Co(OH)2 microspheres consisting of nanoplatelets. Co3O4 microspheres with porous platelets were obtained via subsequent thermal decomposition. These Co3O4 microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co3O4 nanoparticles.

A solvothermal method was developed to prepare on a large scale monodisperse porous β-Co(OH)2 microspheres consisting of nanoplatelets. Co3O4 microspheres with porous platelets were obtained via subsequent thermal decomposition. These Co3O4 microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co3O4 nanoparticles.

A facile hydrothermal route has been developed to prepare graphene–Co3O4 nanocomposites. The graphene–Co3O4 nanocomposite catalyst demonstrates an excellent catalytic activity toward oxygen-reduction reaction including a considerably more positive half-wave potential (−0.23 V) than that of pristine graphene (−0.39 V), as well as higher cathodic currents. More importantly, this catalyst shows better long-term durability than the commercial Pt/C catalyst in an alkaline solution. The preliminary results indicate that the graphene–Co3O4 nanocomposite is an efficient and stable bifunctional catalyst for Li–air batteries and may be an alternative to the high-cost commercial Pt/C catalyst for the ORR/OER in alkaline solutions.

Sr0.95Ce0.05CoO3−δ (SCCO) particles loaded with copper nanoparticles on their surface are shown to be excellent, low-cost, and stable bifunctional catalysts for the oxygen-reduction and oxygen-evolution reactions (ORR and OER) in aqueous solution. Evidence for the presence of Ce3+ and Co2+ as well as Co4+ and Co3+ ions revealed by XPS measurements as well as XRD analysis indicates that a CeCoO2.5 brownmillerite phase may be extruded to the surface. A surface Co4+/Co3+ couple is known to be a good OER catalyst. The performance of the SCCO-based catalysts is better at higher current rates (>0.1 mA cm−2) than that of Vulcan XC-72 and even close to that of the 50% Pt/carbon-black catalyst. This catalyst could be used in a metal/air battery or a PEM fuel cell as an efficient and stable bifunctional catalyst.

In the paper, we find that graphene has a strong dielectric loss, but exhibits very weak attenuation properties to electromagnetic waves due to its high conductivity. As polyaniline nanorods are perpendicularly grown on the surface of graphene by an in situ polymerization process, the electromagnetic absorption properties of the nanocomposite are significantly enhanced. The maximum reflection loss reaches −45.1 dB with a thickness of the absorber of only 2.5 mm. Theoretical simulation in terms of the Cole–Cole dispersion law shows that the Debye relaxation processes in graphene/polyaniline nanorod arrays are improved compared to polyaniline nanorods. The enhanced electromagnetic absorption properties are attributed to the unique structural characteristics and the charge transfer between graphene and polyaniline nanorods. Our results demonstrate that the deposition of other dielectric nanostructures on the surface of graphene sheets is an efficient way to fabricate lightweight materials for strong electromagnetic wave absorbents.

In situ diffusion growth of Fe2(MoO4)3 nanocrystals on the surface of α-MoO3 nanorods was achieved through a facile method. The obtained Fe2(MoO4)3@α-MoO3 nanorods exhibit significantly enhanced ethanol sensing properties compared with those of the pristine α-MoO3 nanorods and the Fe2(MoO4)3 nanoparticles, which are attributed to the improved catalytic properties of Fe2(MoO4)3 at low temperature.

Graphene/porous cobalt nanocomposite was successfully prepared through a facile method, whose hydrogen storage capacity was up to 241.9 mA h g−1 at room temperature, higher than those of graphene and commercial cobalt.

In this work, sub-stoichiometric tungsten oxide W18O49 was first studied as a support for a Pt catalyst. Metallic monoclinic W18O49 nanorods (NRs) with an isotropic morphology can not only improve electron, reactant, and product transport but can also enhance the utilisation of Pt for the methanol oxidation reaction (MOR). The specific activity for the forward peak (If) of Pt/W18O49 was determined to be 1.14 mA cmPt−2, which is approximately 1.4 and 1.8 times higher than that of Pt-black and Pt/C, respectively. On the other hand, the robust W18O49 NRs improve the stability of Pt/W18O49. After a 5000-cycle accelerated durability test, the electrochemical surface area (ECSA) loss rate of Pt/W18O49 was only 27.12%, less than that of Pt-black and Pt/C. Moreover, numerous oxygen vacancies and two valence states of W (W5+ and W6+) were found to co-exist in W18O49, which may promote hydrogen spillover and oxygen buffering. These effects together contributed to improve the anti-poisoning properties of Pt/W18O49 towards the intermediates in the MOR. The peak current ratio of the forward versus the backward (If/Ib) reaction is 1.12 for Pt/W18O49, 0.99 for Pt-black, and 0.79 for Pt/C. It was found that the Magnéli phase W18O49 may be a promising catalyst support for use in the MOR.